Main pole of a fork lift truck

ABSTRACT

A fork lift mainpole comprises inner and outer-most elements on each side, the inner element comprising a U channel having added a shouldered rear flange engaging rollers attached to the outer masts in which the latter rollers are made adjustable by eccentric mountings for immediate and accurate adjustment to avoid shaking.

I United States Patent 11 1 1111 3,782,502

Kobayashi et al. l l Jan. 1, 1974 MAIN POLE OF A FORK LIFT TRUCK 3,070,190 12/1962 Rogers et al 187/95 2,595,120 4/1952 B 187/95 )4 [75] Inventors f f f 3,605,950 9 1971 6352618 187 9 Sakagufhh Kusesa TPnomshl; 3,414,086 12/1968 Ulinski 187 95 x Masah Maeda, 1 all of Japan 3,358,791 12/1967 Goodacre 187 9 [73] Assignee: Nissan Shatai Co., Ltd.,

- Kanagawaken Japan Primary Examiner-Allen N. Knotvles Attorney-Bever1dge & De Grandi [22] Filed: Aug. 30, 1971 [2]] Appl. N0.: 176,057 [57] ABSTRACT A fork lift mainpole comprises inner and outer-most [52] U.S. Cl. 187/9, 187/95 elements on each side, the n r element mprising a [51] Int. Cl B66b 7/02 U channel having added a shouldered ar flang n- [58] Field of Search 187/9, 95 g g g er hed to the outer masts in which the latter rollers are made adjustable by eecentric mount- [56] Refer Cit d ings for immediate and accurate adjustment to avoid UNITED STATES PATENTS Shakmg- 2,936,047 5/1960 Quayle 187/95 3 Claims, 4 Drawing Figures PATENTEDJAN Hal-14 SHEET -1 or 2 INVENTORS moi-ax! KoBAYAS/l "Mme 1 54/44 Guam mASAH/RO MAEba BY 3M4 ATTORNEYS PAIENIEDJAN 1 4 3.782.502

I SHEET 2 BF 2 INVENTORS Moro/u Mob/" 4:!!!

07434010 54/ Gaol-I MASAHIIRQ M4 04 ATTORNEYj Y 1 MAIN POLE OF A FORK LIFT TRUCK The present invention relates to the main pole of a fork lift truck. In a main pole of a conventional fork lift truck, the masts tend to become loose because of manufacturing errors and distortion of the masts or the wear of supporting rollers, resulting in poor stability of the car body and possibility of falling and damaging of the load. Further since the masts have a great weight, even a slight looseness of it causes a large inertia impact, accelerating not only the damages of the supporting rollers and the masts but also the fatigue of the driver when driving on a rough road, thus making a serious disadvantage of the conventional fork lift truck.

With a view to eliminating these difficulties and defects, the present invention provides a main pole of a fork lift truck having masts capable of simple and correct adjustment of their looseness and being kept always in the best operating conditions and at the same time capable of absorbing forces from the back and from the side.

For the purposes of illustration a typical embodiment of the invention is shown in the accompanying drawings in which FIG. 1 is a slant view of the embodiment,

FIG. 2 is a side elevation of the essential part thereof,

FIG. 3 is a sectional view taken along the line A A in FIG. 2 and FIG. 4 is a sectional view taken along the line B B in FIG. 2.

a is the body of a fork lift truck and b shows a fork lift provided at the front of the body a. 1 is right and left outside masts of the fork lift b, made of U-steel bars disposed with their openings directed toward each other. Within these outside masts there are disposed inside masts 2 made of U-steel bars with their openings directed inward, the inside masts being capable of free up-down movement. On the inside at the upper portion of the outside masts 1 and on the out side at the lower portion of the inner masts 2 there are provided supporting rollers 3 and 4-. The supporting roller 3 rolls in contact with a front flat portion 5a of an outer flange 5 provided as projection above the mounting position of the supporting roller 4 on the outside of the inner mast 2, while the supporting roller 4 rolls in contact with a flat front portion 6a of a rear flange 6 of the outer mast I. The upper portions of the front and rear flanges 6 and 7 of the outer mast 1 are removed, and at the rear edge of the outer mast there is provided a bracket 8. On the inside of said bracket 8 there is pivotally mounted on a shaft a supporting roller 9 which rolls in contact with a rear flat portion 5b of the outside flange 5 of the inner mast 2, the shaft 10 being eccentrically fixed to the central supporting axis portion 11 of the supporting roller 9. The portion of the surface of said rear flat portion 5b in contact with the supporting roller 9 is formed like a step or a shoulder 12 whose inside edge is in contact with the periphery of the roller 9. 13 is a supporting frame of the fork l4, and on the side of this supporting frame 13 there is provided a supporting roller 16 which rolls in contact with the rear flat face portion a of the front flange 15 of the inner mast 2. 17 is a chain for up-down operation.

According to the present invention as described above, the supporting roller mounted on the outside of the lower portion of the inner mast rolls in contact with the front side of the rear flange of the outer mast, and

the supporting roller mounted on the inside of the upper portion of the outer mast rolls in contact with the front side of the outside flange of the inner mast, while further the back supporting roller rotatably mounted to the bracket extended from the rear edge of the outer mast rolls in contact with the rear side of the outside flange of the inner mast.

Thus the outer and inner masts are supported by rolling contact at three points, and accordingly even when the center of gravity of the load on the fork is deviating forward from the center of the fork, the inner mast is prevented from shaking back and forth against the outer mast. And furthermore, said back supporting roller rolls in contact with the shoulder-shaped surface of the outer flange, so that the inner mast is also prevented from right-left shaking. Further, since the back supporting roller is pivotally mounted eccentrically on the bracket extending from the rear edge of the outer mast, it is possible to adjust freely the degree of contact between said back supporting roller and the outside flange of the inner mast, greatly facilitating the fabrication of the fork lift and the inclination adjustment of the inner mast against the outer mast.

According to the present invention it is thus possible to prevent easily and correctly any inclination and shaking of masts of the fork lift truck, providing advantages that the truck can run on rough road stably without the fear of falling, damage or break of load and that breaks of rollers and masts are also prevented.

What is claimed is:

1. A mast structure for a fork lift truck including an outer mast comprising spaced apart outer guide members braced apart in parallel relationship and secured to a truck body whereof each member comprises a fore and aft web with laterally extending flanges comprising a U-channel each channel facing toward the channel of the other member of the pair throughout the lower portion of the length thereof and having said flanges removed throughout a top portion of the length thereof, a mounting member comprising a rearward extension of said web in said top portion of each said member for supporting an anti-shake roller substantially aft of the rear flange of said U-channel at the top portion of each member, a load supporting roller having a fixed axis attached perpendicular to the web in said top portion of each member, an anti-shake roller attached to said web adjacent to said load-supporting roller and at a position spaced forward therefrom sufficiently to accommodate therebetween a flange member of an inner guide member, eccentrically adjustable mounting means comprising a bearing for said anti-shake roller attached to said web extension and adjustable by rotation thereof to vary the spacing between said rollers for receiving said flange member in adjustably firm contact, an inner guide member adjacent and parallel to each said outer member and having a web portion and fore and aft flange portions forming a U-channel each facing the U- channel of the other said inner guide member, said guide members being secured together in spaced relationship to form an inner mast, a load-supporting roller on a fixed axis perpendicular to said web portion of each said inner guide member at the lower end thereof each last said roller engaging the channel flanges of the adjacent said outer guide member preventing fore and aft motion thereof, a further load-supporting flange member comprising substantially a reverse flange opposite said channel flange at the after edge of said web 3 portion of each inner guide member throughout the length of each inner member except at a roller holding portion at the bottom thereof, being innermast support means held between said rollers at the top of the outermast, a further load supporting roller having an axis fixed perpendicular to said web of each said inner member at said bottom portion positioned between said flanges of the adjacent outer guide member, being means supporting the inner guide member at the lower end thereof during vertical displacement along the outer member, a load carriage including a pair of vertical supports bearing upper and lower pairs of rollers engaging said channel flanges of said inner guide members,

means including rigid bracing of said vertical supports for preventing separation of last said pairs of rollers, and further means for preventing lateral shaking of said load carriage with respect to the outer mast comprising a shoulder portion of each said reverse flange being arranged to engage the inner face of said anti-shake roller at the periphery thereof being attached to said outer member at its top portion such that the anti-shake roller engages said reverse flange both along its rearward face and a said shoulder facing outwardly to thereby prevent lateral displacement of the inner mast in respect to the outer mast at its upper end.

2. A mast structure according to claim 1 said inner guide members being of substantially uniform section except for removal of said flanges forming a channel over a length not greatly exceeding the dimensions of said rollers attached perpendicularly to the bottom end thereof.

3. A mast structure according to claim 1 said eccentrically adjustable mounting means comprising a shaft comprising the bearing of said anti shake roller and an attached mounting shaft parallelthereto and noneccentric therewith engaging the web at positions variable with shaft rotation.

' UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,782,502 Dated January 1, 197A Motoki Kobayashi, Masaoki Sakaguchi and Inventofls) Masahiro Maeda It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the inventors names, "Motori Kobayashi" should read "Motoki ,Kobayashi.

Signed and sealed. this 30th da of April LUNA.

(SEAL) Attest:

EDWARD M.FLATCHER,JH. C. MARSHALL DAMN Attesting Officer v Commissioner of Patents. 

1. A mast structure for a fork lift truck including an outer mast comprising spaced apart outer guide members braced apart in parallel relationship and secured to a truck body whereof each member comprises a fore and aft web with laterally extending flanges comprising a U-channel each channel facing toward the channel of the other member of the pair throughout the lower portion of the length thereof and having said flanges removed throughout a top portion of the length thereof, a mounting member comprising a rearward extension of said web in said top portion of each said member for supporting an anti-shake roller substantially aft of the rear flange of said U-channel at the top portion of each member, a load supporting roller having a fixed axis attached perpendicular to the web in said top portion of each member, an anti-shake roller attached to said web adjacent to said load-supporting roller and at a position spaced forward therefrom sufficiently to accommodate therebetween a flange member of an inner guide member, eccentrically adjustable mounting means comprising a bearing for said anti-shake roller attached to said web extension and adjustable by rotation thereof to vary the spacing between said rollers for receiving said flange member in adjustably firm contact, an inner guide member adjacent and parallel to each said outer member and having a web portion and fore and aft flange portions forming a U-channel each facing the U-channel of the other said inner guide member, said guide members being secured together in spaced relationship to form an inner mast, a load-supporting roller on a fixed axis perpendicular to said web portion of each said inner guide member at the lower end thereof each last said roller engaging the channel flanges of the adjacent said outer guide member preventing fore and aft motion thereof, a further load-supporting flange member comprising substantially a reverse flange opposite said channel flange at the after edge of said web poRtion of each inner guide member throughout the length of each inner member except at a roller holding portion at the bottom thereof, being innermast support means held between said rollers at the top of the outermast, a further load supporting roller having an axis fixed perpendicular to said web of each said inner member at said bottom portion positioned between said flanges of the adjacent outer guide member, being means supporting the inner guide member at the lower end thereof during vertical displacement along the outer member, a load carriage including a pair of vertical supports bearing upper and lower pairs of rollers engaging said channel flanges of said inner guide members, means including rigid bracing of said vertical supports for preventing separation of last said pairs of rollers, and further means for preventing lateral shaking of said load carriage with respect to the outer mast comprising a shoulder portion of each said reverse flange being arranged to engage the inner face of said anti-shake roller at the periphery thereof being attached to said outer member at its top portion such that the anti-shake roller engages said reverse flange both along its rearward face and a said shoulder facing outwardly to thereby prevent lateral displacement of the inner mast in respect to the outer mast at its upper end.
 2. A mast structure according to claim 1 said inner guide members being of substantially uniform section except for removal of said flanges forming a channel over a length not greatly exceeding the dimensions of said rollers attached perpendicularly to the bottom end thereof.
 3. A mast structure according to claim 1 said eccentrically adjustable mounting means comprising a shaft comprising the bearing of said anti shake roller and an attached mounting shaft parallel thereto and non-eccentric therewith engaging the web at positions variable with shaft rotation. 